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Journal Articles Surface and Interface Analysis Year : 2010

Corrosion behaviour of mechanically polished AA7075-T6 aluminium alloy

Abstract

In the present study, the effects of mechanical polishing on the microstructure and corrosion behaviour of AA7075 aluminium alloy are investigated. It was found that a nano-grained, near-surface deformed layer, up to 400 nm thickness, is developed due to significant surface shear stress during mechanically polishing. Within the near-surface deformed layer, the alloying elements have been redistributed and the microstructure of the alloy is modified; in particular, the normal MgZn2 particles for T6 are absent. However, segregation bands, approximately 10-nm thick, containing mainly zinc, are found at the grain boundaries within the near-surface deformed layer. The presence of such segregation bands promoted localised corrosion along the grain boundaries within the near-surface deformed layer due to microgalvanic action. During anodic polarisation of mechanically polished alloy in sodium chloride solution, two breakdown potentials were observed at −750 mV and −700 mV, respectively. The first breakdown potential is associated with an increased electrochemical activity of the near-surface deformed layer, and the second breakdown potential is associated with typical pitting of the bulk alloy.
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Dates and versions

hal-03551001 , version 1 (01-02-2022)

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Yanwen Liu, Adrien Laurino, Teruo Hashimoto, Xiaorong Zhou, Peter Skeldon, et al.. Corrosion behaviour of mechanically polished AA7075-T6 aluminium alloy. Surface and Interface Analysis, 2010, 42 (4), pp.185-188. ⟨10.1002/sia.3136⟩. ⟨hal-03551001⟩
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